Membrane-based calorimetry with Coulomb blockade thermometry

Materials that exhibit new physics are often grown in thin film form, or as nanoscale single crystals. Thermodynamic measurements can give clear information about phase transitions in the material, but challenges exist for thermal measurements on this scale. The requirement for a thermometer to have low thermal mass, be magnetic field independent and the capability for primary thermometry to overcome intrinsic calibration challenges lead us to develop membrane based calorimetry, with Coulomb blockade thermometry [1]. Nanofabrication techniques were used to fabricate Al/AlO₃/Al tunnel junctions on SiN membranes. We succeeded in fabricating a primary thermometer covering the temperature range from below 150mK to above 30K, allowing for resolving heat capacities well below 1 nJ/K. We will report on commissioning the thermometer and setup for the first measurements on strongly correlated nanoscale samples.

[1] J. P. Kauppinen et al., Rev. Sci. Instrum., 69, 4166 (1998)